Explain the process by which oxygen in the atmosphere is inhaled.
Before inhalation – air pressure inside the lungs is equal to the air pressure of the atmosphere
1. Diaphragm contracts and flattens lowers dome
2. External intercostals contract and pull ribs upward and outward
3. When the diaphragm and external intercostals do this, the vertical diameter and volume of the thoracic
4. As the thoracic cavity increases, the pressure in the lungs decrease makes it lower than the
5. Air rushes into the lungs
Describe in detail, the route this oxygen will follow to end up in the alveoli.
External nares internal nares pharynx larynx trachea right and left primary bronchi secondary
bronchi tertiary bronchi bronchioles terminal bronchioles pulmonary lobules alveoli
1. Oxygen is inhaled through external nares
2. Air passes through the nasal cavity
3. As air enters the nostrils, it passes through “shelves” called the nasal conchae which filters the air
4. Air moves through the pharynx through the glottis, where the epiglottis is open allowing air the move
through to the larynx
5. Larynx is a short passageway for air to the lungs, and connects the pharynx with the trachea
6. The trachea extends from the larynx, and then divides into the right and left primary bronchi in the lungs.
7. Primary bronchi divides to form the secondary and tertiary bronchi
8. Tertiary bronchi divide into bronchioles that branch again into terminal bronchioles which form
9. Each lobule has alveoli, a collection of cup-shaped pouches, and is the site of gas exchange.
Explain in detail how the oxygen enters the blood.
Air pharynx larynx trachea left/right bronchus bronchioles alveoli capillaries
Capillaries surrounding the alveoli
Since alveoli and capillaries are one cell thick, oxygen in the alveoli easily diffuses into the capillaries
Carbon dioxide is collected from cells throughout the body and diffused out of capillaries and into alveoli,
then breathed out.
Oxygen-rich capillaries deliver oxygen to various tissues in the body
Explain how oxygen is transported in the blood.
Only a small amount of oxygen is dissolved in the plasma
Oxygen does not easily dissolve in water so only a little is carried in the blood plasma.
Most of the oxygen is atta